Do mechanical watch movements need to be set with rubies?

　　The rubies we refer to in ruby bearings are generally synthetic, primarily composed of aluminium oxide. They feature characteristics such as a hard and uniform texture, ease of processing, and a variety of colours, sharing the same properties as natural rubies. I wonder if you have ever considered why mechanical watch movements are set with rubies?

　　Reasons for setting rubies in mechanical watch movements

　　1, Consumer Demands

　　All products ultimately exist to satisfy consumption. In the eyes of consumers, timepieces featuring gemstones (even synthetic ones) enhance face value and prestige. Watchmakers quickly caught on to this business opportunity and began setting rubies into movements. Ruby bearings mainly fall into four categories: one is used as pivot holes, commonly known as jewel holes, which are set in specific parts to bring the wheel axle and the jewel hole into contact; another is used as cover plates, commonly known as endstones, which act like mechanical bearings to limit the vertical play of the pivots; yet another is the circular diamond used as a pallet jewel. Even in an ordinary manually wound mechanical watch, the number of jewels can range from a minimum of 14 to a maximum of 19, while automatic winding and complicated mechanical timepieces have even more.

　　2, Historical Background

　　Let us begin with the history of rubies. In the 18th century, England was the cradle of high-quality clocks, where watchmakers used small particles of ruby (known as gemstones) as bearings for balance pivots. The technique of drilling rubies was first created by the Swiss optical instrument maker and astronomer Nicolas Fatio, who went to England hoping to secure a "royal privilege" for this invention. However, the British claimed that the technology was already in use, and ultimately he did not obtain the privilege, though his technique was adopted by other craftsmen—a technology that allowed the British Empire to maintain its advantage in the watchmaking industry. The turning point came when master watchmaker Abraham-Louis Breguet brought British watchmaking technology back to France. Since then, rubies have been universally used in watches.

　　3, Technical Reasons

　　The setting of rubies in movements was initially based on technical reasons, as the operation of a mechanical watch movement relies on the continuous transmission of power through various gears. Before the vital function of rubies was understood, the pivots of the escape wheel, the pallet fork, the balance staff, and the wheels of the gear train were pivoted directly into holes within the brass plates. These holes featured small oil sinks where oil flowed in to lubricate the pivots. Over time, dust and other particles from the air entered, forming an abrasive substance that gradually wore away the softer brass of the plates and even the harder steel pivots. Watchmakers thus realised the need to find a material harder than brass that could withstand the wear of the pivots. This material was the ruby, a substance second only to diamond in hardness. Natural rubies are highly scarce, so synthetic versions are produced for use in watches.

　　Summary: Rubies undoubtedly enhance the overall quality of a product, and high-quality watches cannot do without them. However, ruby bearings are not the exclusive preserve of high-end watches; with industrialisation, the use of ruby bearings in watch movements has become very common. At the same time, a high number of rubies does not necessarily indicate high quality; true high quality is invariably something that has survived the test of time and validation.